The present invention relates to the field of wireless communication technology, and more specifically, to a method for generating consistent cryptographic keys based on wireless channel features.
As wireless communication technology develops rapidly and penetrates into society and economy, the security of wireless services and the importance of privacy protection get increasingly prominent. Due to the openness of wireless channels, the air interface of a wireless communication system is vulnerable to eavesdropping, falsification, deletion and other types of attacks and thus becomes a weak link of the wireless communication system.
Coupled with broadcast properties, wireless channels also have nature such as randomness, privacy and reciprocity. Existing methods for generating cryptographic keys based on wireless channel features are based on the reciprocity of wireless channels, i.e. channel status information of both communication parties has consistency in channel coherence intervals, so cryptographic keys are generated using estimated values of channel status information. These methods contain drawbacks. That is, since the channel estimate inconsistency between both communication parties caused by noise and interference is not taken into consideration, respective cryptographic keys generated by both communication parties are not necessarily consistent. Or consideration is given to the channel estimate inconsistency caused by noise and interference; nevertheless, it is believed, mistakenly, that noise and interference can be tackled and consistent estimated values of channel status information are achieved by generating and sending to the other party check bit information through specific channel encoding and then the other party decoding based on own channel estimated values and the received check bit information, whereas the error correction performance of a preset specific channel encoding scheme is rather limited and does not match current channel status; thus, it is difficult to ensure the consistency between channel estimated values under massive changes of Signal-to-Noise ratio (SNR) caused by rapid channel changes, nor to ensure the consistency between cryptographic keys generated by both communication parties.
In a real system, as there exists interference such as thermal noise, error of the channel status information estimate is necessarily present, so that channel status estimated values of both communication parties might be inconsistent. When the channel estimate error of both communication parties is great enough to damage the cryptographic key consistency, how to ensure design cryptographic key negotiation technology and thus ensure the cryptographic key consistency becomes a critical problem as to the physical layer security.